In the past year two studies have been completed. The first has examined prostate specific antigen as a marker of prostatic cancer. Longitudinal analyses demonstrated a significant age adjusted difference in rate of change in PSA between subjects with prostate cancer, BPH and controls. At a time when PSA did not differ between BPH and prostate cancer subjects (5 years before diagnosis), rate of change in PSA was significantly greater in subjects with prostate cancer. The findings suggest that of change in PSA may be a sensitive and specific early marker for the development of prostate cancer. The second study estimated the PSA growth curves of BLSA participants with no evidence of prostate disease, BPH cases, and prostate cancer cases. Control participants exhibited minimal change in PSA thus suggesting that BPH is not a natural outcome of normal prostate growth, but is a separate pathogenic process. BPH cases showed a gradual and continuing acceleration in PSA with increasing age. Cancer cases exhibited an early slow linear phase of PSA growth followed by a rapid exponential growth phase.